| 200 | ( | 1 | + | r | − | 2 | × | 199 200 | r | ) | = | 1 | + | r |
| 方程左边 = | 200 | × | 1 | + | 200 | r | − | 200 | × | 2 | × | 199 200 | r |
| = | 200 | + | 200 | r | − | 398 | r |
| = | 200 | − | 198 | r |
| 200 | − | 198 | r | = | 1 | + | r |
| - | 198 | r | − | r | = | 1 | − | 200 |
| - | 199 | r | = | 1 | − | 200 |
| - | 199 | r | = | - | 199 |
| 199 | = | 199 | r |
| 199 | r | = | 199 |
| r | = | 199 | ÷ | 199 |
| = | 199 | × | 1 199 |
| r | = | 199 199 |
| r | = | 1 |